The present invention relates to a method for generating a glass ceramic composite structure.
A method for producing a composite structure consisting of a zero-expansion material, and a method for producing the same, are known from WO 2006/034775 A1.
That publication describes different components, consisting of a zero-expansion material, for example of a LAS glass ceramic, that are bonded together by at least one adhesive layer. Any disadvantages are to be kept as small as possible by keeping the adhesive layer used as thin as possible. However, such a bond of course does not stand high temperatures and in addition has relatively low stability. Also, the advantageous properties of the zero-expansion materials are influenced detrimentally.
DE 198 21 679 A1 discloses a method for joining fiber-reinforced glass or glass ceramic materials to other materials, such as ceramic materials, where the glass or glass ceramic materials and the other materials are pressed together at a boundary surface between the two materials at high temperatures to form a heat fusion joint. The hot-pressing operation is intended to improve the joint.
A disadvantage of that method is seen in the relatively high expense connected with the hot-pressing operation. Further, pressing can be realized only with difficulty in the case of large components. Finally, the strength of the joint so produced is limited.
According to JP 63319230 a bonding material used for joining components made from glass or glass ceramics consists of a mixture of glass powder having a low softening point and a glass powder having a higher softening point, and the powder mixture serves as a joining partner between the components which is subsequently solidified by sintering and subjected to a crystallization treatment.
This process is relatively expensive, and still does not yield a high-strength joint due to the sintering process.
According to JP 2005061747 a plurality of components made from glass that are to be bonded together, are softened in a furnace and fused so that they are bonded one to the other. The structure so obtained is then heat-treated and crystallized.
Similarly, US 2005/0014008 A1 provides that a plurality of components made from glass that are to be bonded together, are initially joined by welding in their green glass condition and are then ceramized.
In order to do so, the edges of the two components must be heated up to a temperature far above the softening point, and this purposefully at the same time and homogeneously over their full length, in order to ensure that a strong bond is achieved when the two edges are pressed together. This is extremely difficult, especially in the case of long joining edges. In addition, there is only little time (in the order of seconds) available to complete the joining operation before the undesirable ceramization process of the green glass components begins.
For joining glass ceramics, there have also been known cementation processes of the type described, for example, by U.S. Pat. No. 3,715,196.
In that case, the strength of the bond depends on the adherence of the cement and its mechanical properties. And there is no real zero-expansion cement that would be capable of bonding together two glass ceramic materials with zero-expansion characteristics. Moreover, such a bond as a rule does not stand the high thermal stresses which normally would be tolerated by glass ceramic materials.